/*
 * Copyright (c) 2009-2011, Salvatore Sanfilippo <antirez at gmail dot com>
 * Copyright (c) 2010-2011, Pieter Noordhuis <pcnoordhuis at gmail dot com>
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *   * Neither the name of Redis nor the names of its contributors may be used
 *     to endorse or promote products derived from this software without
 *     specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "fmacros.h"
#include <string.h>
#include <stdlib.h>
#ifndef _MSC_VER
#include <unistd.h>
#endif
#include <assert.h>
#include <errno.h>
#include <ctype.h>

#include "read.h"
#include "sds.h"

static void __redisReaderSetError(redisReader *r, int type, const char *str)
{
	size_t len;

	if (r->reply != NULL && r->fn && r->fn->freeObject)
	{
		r->fn->freeObject(r->reply);
		r->reply = NULL;
	}

	/* Clear input buffer on errors. */
	if (r->buf != NULL)
	{
		sdsfree(r->buf);
		r->buf = NULL;
		r->pos = r->len = 0;
	}

	/* Reset task stack. */
	r->ridx = -1;

	/* Set error. */
	r->err = type;
	len = strlen(str);
	len = len < (sizeof(r->errstr) - 1) ? len : (sizeof(r->errstr) - 1);
	memcpy(r->errstr, str, len);
	r->errstr[len] = '\0';
}

static size_t chrtos(char *buf, size_t size, char byte)
{
	size_t len = 0;

	switch (byte)
	{
	case '\\':
	case '"':
		len = snprintf(buf, size, "\"\\%c\"", byte);
		break;
	case '\n':
		len = snprintf(buf, size, "\"\\n\"");
		break;
	case '\r':
		len = snprintf(buf, size, "\"\\r\"");
		break;
	case '\t':
		len = snprintf(buf, size, "\"\\t\"");
		break;
	case '\a':
		len = snprintf(buf, size, "\"\\a\"");
		break;
	case '\b':
		len = snprintf(buf, size, "\"\\b\"");
		break;
	default:
		if (isprint(byte))
			len = snprintf(buf, size, "\"%c\"", byte);
		else
			len = snprintf(buf, size, "\"\\x%02x\"", (unsigned char) byte);
		break;
	}

	return len;
}

static void __redisReaderSetErrorProtocolByte(redisReader *r, char byte)
{
	char cbuf[8], sbuf[128];

	chrtos(cbuf, sizeof(cbuf), byte);
	snprintf(sbuf, sizeof(sbuf), "Protocol error, got %s as reply type byte",
			cbuf);
	__redisReaderSetError(r, REDIS_ERR_PROTOCOL, sbuf);
}

static void __redisReaderSetErrorOOM(redisReader *r)
{
	__redisReaderSetError(r, REDIS_ERR_OOM, "Out of memory");
}

static char *readBytes(redisReader *r, unsigned int bytes)
{
	char *p;
	if (r->len - r->pos >= bytes)
	{
		p = r->buf + r->pos;
		r->pos += bytes;
		return p;
	}
	return NULL;
}

/* Find pointer to \r\n. */
static char *seekNewline(char *s, size_t len)
{
	int pos = 0;
	int _len = len - 1;

	/* Position should be < len-1 because the character at "pos" should be
	 * followed by a \n. Note that strchr cannot be used because it doesn't
	 * allow to search a limited length and the buffer that is being searched
	 * might not have a trailing NULL character. */
	while (pos < _len)
	{
		while (pos < _len && s[pos] != '\r')
			pos++;
		if (pos == _len)
		{
			/* Not found. */
			return NULL;
		} else
		{
			if (s[pos + 1] == '\n')
			{
				/* Found. */
				return s + pos;
			} else
			{
				/* Continue searching. */
				pos++;
			}
		}
	}
	return NULL;
}

/* Read a long long value starting at *s, under the assumption that it will be
 * terminated by \r\n. Ambiguously returns -1 for unexpected input. */
static long long readLongLong(char *s)
{
	long long v = 0;
	int dec, mult = 1;
	char c;

	if (*s == '-')
	{
		mult = -1;
		s++;
	} else if (*s == '+')
	{
		mult = 1;
		s++;
	}

	while ((c = *(s++)) != '\r')
	{
		dec = c - '0';
		if (dec >= 0 && dec < 10)
		{
			v *= 10;
			v += dec;
		} else
		{
			/* Should not happen... */
			return -1;
		}
	}

	return mult * v;
}

static char *readLine(redisReader *r, int *_len)
{
	char *p, *s;
	int len;

	p = r->buf + r->pos;
	s = seekNewline(p, (r->len - r->pos));
	if (s != NULL)
	{
		len = s - (r->buf + r->pos);
		r->pos += len + 2; /* skip \r\n */
		if (_len)
			*_len = len;
		return p;
	}
	return NULL;
}

static void moveToNextTask(redisReader *r)
{
	redisReadTask *cur, *prv;
	while (r->ridx >= 0)
	{
		/* Return a.s.a.p. when the stack is now empty. */
		if (r->ridx == 0)
		{
			r->ridx--;
			return;
		}

		cur = &(r->rstack[r->ridx]);
		prv = &(r->rstack[r->ridx - 1]);
		assert(prv->type == REDIS_REPLY_ARRAY);
		if (cur->idx == prv->elements - 1)
		{
			r->ridx--;
		} else
		{
			/* Reset the type because the next item can be anything */
			assert(cur->idx < prv->elements);
			cur->type = -1;
			cur->elements = -1;
			cur->idx++;
			return;
		}
	}
}

static int processLineItem(redisReader *r)
{
	redisReadTask *cur = &(r->rstack[r->ridx]);
	void *obj;
	char *p;
	int len;

	if ((p = readLine(r, &len)) != NULL)
	{
		if (cur->type == REDIS_REPLY_INTEGER)
		{
			if (r->fn && r->fn->createInteger)
				obj = r->fn->createInteger(cur, readLongLong(p));
			else
				obj = (void*) REDIS_REPLY_INTEGER;
		} else
		{
			/* Type will be error or status. */
			if (r->fn && r->fn->createString)
				obj = r->fn->createString(cur, p, len);
			else
				obj = (void*) (size_t) (cur->type);
		}

		if (obj == NULL)
		{
			__redisReaderSetErrorOOM(r);
			return REDIS_ERR;
		}

		/* Set reply if this is the root object. */
		if (r->ridx == 0)
			r->reply = obj;
		moveToNextTask(r);
		return REDIS_OK;
	}

	return REDIS_ERR;
}

static int processBulkItem(redisReader *r)
{
	redisReadTask *cur = &(r->rstack[r->ridx]);
	void *obj = NULL;
	char *p, *s;
	long len;
	unsigned long bytelen;
	int success = 0;

	p = r->buf + r->pos;
	s = seekNewline(p, r->len - r->pos);
	if (s != NULL)
	{
		p = r->buf + r->pos;
		bytelen = s - (r->buf + r->pos) + 2; /* include \r\n */
		len = readLongLong(p);

		if (len < 0)
		{
			/* The nil object can always be created. */
			if (r->fn && r->fn->createNil)
				obj = r->fn->createNil(cur);
			else
				obj = (void*) REDIS_REPLY_NIL;
			success = 1;
		} else
		{
			/* Only continue when the buffer contains the entire bulk item. */
			bytelen += len + 2; /* include \r\n */
			if (r->pos + bytelen <= r->len)
			{
				if (r->fn && r->fn->createString)
					obj = r->fn->createString(cur, s + 2, len);
				else
					obj = (void*) REDIS_REPLY_STRING;
				success = 1;
			}
		}

		/* Proceed when obj was created. */
		if (success)
		{
			if (obj == NULL)
			{
				__redisReaderSetErrorOOM(r);
				return REDIS_ERR;
			}

			r->pos += bytelen;

			/* Set reply if this is the root object. */
			if (r->ridx == 0)
				r->reply = obj;
			moveToNextTask(r);
			return REDIS_OK;
		}
	}

	return REDIS_ERR;
}

static int processMultiBulkItem(redisReader *r)
{
	redisReadTask *cur = &(r->rstack[r->ridx]);
	void *obj;
	char *p;
	long elements;
	int root = 0;

	/* Set error for nested multi bulks with depth > 7 */
	if (r->ridx == 8)
	{
		__redisReaderSetError(r, REDIS_ERR_PROTOCOL,
				"No support for nested multi bulk replies with depth > 7");
		return REDIS_ERR;
	}

	if ((p = readLine(r, NULL)) != NULL)
	{
		elements = readLongLong(p);
		root = (r->ridx == 0);

		if (elements == -1)
		{
			if (r->fn && r->fn->createNil)
				obj = r->fn->createNil(cur);
			else
				obj = (void*) REDIS_REPLY_NIL;

			if (obj == NULL)
			{
				__redisReaderSetErrorOOM(r);
				return REDIS_ERR;
			}

			moveToNextTask(r);
		} else
		{
			if (r->fn && r->fn->createArray)
				obj = r->fn->createArray(cur, elements);
			else
				obj = (void*) REDIS_REPLY_ARRAY;

			if (obj == NULL)
			{
				__redisReaderSetErrorOOM(r);
				return REDIS_ERR;
			}

			/* Modify task stack when there are more than 0 elements. */
			if (elements > 0)
			{
				cur->elements = elements;
				cur->obj = obj;
				r->ridx++;
				r->rstack[r->ridx].type = -1;
				r->rstack[r->ridx].elements = -1;
				r->rstack[r->ridx].idx = 0;
				r->rstack[r->ridx].obj = NULL;
				r->rstack[r->ridx].parent = cur;
				r->rstack[r->ridx].privdata = r->privdata;
			} else
			{
				moveToNextTask(r);
			}
		}

		/* Set reply if this is the root object. */
		if (root)
			r->reply = obj;
		return REDIS_OK;
	}

	return REDIS_ERR;
}

static int processItem(redisReader *r)
{
	redisReadTask *cur = &(r->rstack[r->ridx]);
	char *p;

	/* check if we need to read type */
	if (cur->type < 0)
	{
		if ((p = readBytes(r, 1)) != NULL)
		{
			switch (p[0])
			{
			case '-':
				cur->type = REDIS_REPLY_ERROR;
				break;
			case '+':
				cur->type = REDIS_REPLY_STATUS;
				break;
			case ':':
				cur->type = REDIS_REPLY_INTEGER;
				break;
			case '$':
				cur->type = REDIS_REPLY_STRING;
				break;
			case '*':
				cur->type = REDIS_REPLY_ARRAY;
				break;
			default:
				__redisReaderSetErrorProtocolByte(r, *p);
				return REDIS_ERR;
			}
		} else
		{
			/* could not consume 1 byte */
			return REDIS_ERR;
		}
	}

	/* process typed item */
	switch (cur->type)
	{
	case REDIS_REPLY_ERROR:
	case REDIS_REPLY_STATUS:
	case REDIS_REPLY_INTEGER:
		return processLineItem(r);
	case REDIS_REPLY_STRING:
		return processBulkItem(r);
	case REDIS_REPLY_ARRAY:
		return processMultiBulkItem(r);
	default:
		assert(NULL);
		return REDIS_ERR; /* Avoid warning. */
	}
}

redisReader *redisReaderCreateWithFunctions(redisReplyObjectFunctions *fn)
{
	redisReader *r;

	r = calloc(sizeof(redisReader), 1);
	if (r == NULL)
		return NULL;

	r->err = 0;
	r->errstr[0] = '\0';
	r->fn = fn;
	r->buf = sdsempty();
	r->maxbuf = REDIS_READER_MAX_BUF;
	if (r->buf == NULL)
	{
		free(r);
		return NULL;
	}

	r->ridx = -1;
	return r;
}

void redisReaderFree(redisReader *r)
{
	if (r->reply != NULL && r->fn && r->fn->freeObject)
		r->fn->freeObject(r->reply);
	if (r->buf != NULL)
		sdsfree(r->buf);
	free(r);
}

int redisReaderFeed(redisReader *r, const char *buf, size_t len)
{
	sds newbuf;

	/* Return early when this reader is in an erroneous state. */
	if (r->err)
		return REDIS_ERR;

	/* Copy the provided buffer. */
	if (buf != NULL && len >= 1)
	{
		/* Destroy internal buffer when it is empty and is quite large. */
		if (r->len == 0 && r->maxbuf != 0 && sdsavail(r->buf) > r->maxbuf)
		{
			sdsfree(r->buf);
			r->buf = sdsempty();
			r->pos = 0;

			/* r->buf should not be NULL since we just free'd a larger one. */
			assert(r->buf != NULL);
		}

		newbuf = sdscatlen(r->buf, buf, len);
		if (newbuf == NULL)
		{
			__redisReaderSetErrorOOM(r);
			return REDIS_ERR;
		}

		r->buf = newbuf;
		r->len = sdslen(r->buf);
	}

	return REDIS_OK;
}

int redisReaderGetReply(redisReader *r, void **reply)
{
	/* Default target pointer to NULL. */
	if (reply != NULL)
		*reply = NULL;

	/* Return early when this reader is in an erroneous state. */
	if (r->err)
		return REDIS_ERR;

	/* When the buffer is empty, there will never be a reply. */
	if (r->len == 0)
		return REDIS_OK;

	/* Set first item to process when the stack is empty. */
	if (r->ridx == -1)
	{
		r->rstack[0].type = -1;
		r->rstack[0].elements = -1;
		r->rstack[0].idx = -1;
		r->rstack[0].obj = NULL;
		r->rstack[0].parent = NULL;
		r->rstack[0].privdata = r->privdata;
		r->ridx = 0;
	}

	/* Process items in reply. */
	while (r->ridx >= 0)
		if (processItem(r) != REDIS_OK)
			break;

	/* Return ASAP when an error occurred. */
	if (r->err)
		return REDIS_ERR;

	/* Discard part of the buffer when we've consumed at least 1k, to avoid
	 * doing unnecessary calls to memmove() in sds.c. */
	if (r->pos >= 1024)
	{
		sdsrange(r->buf, r->pos, -1);
		r->pos = 0;
		r->len = sdslen(r->buf);
	}

	/* Emit a reply when there is one. */
	if (r->ridx == -1)
	{
		if (reply != NULL)
			*reply = r->reply;
		r->reply = NULL;
	}
	return REDIS_OK;
}
